The rational design of a redox-active mixed ion/electron conductor as a multi-functional binder for lithium-ion batteries

Abstract

A redox-active mixed ion and electron conductor (redox-active MIEC) is presented as a binder for the lithium titanate anodes of lithium-ion batteries. The redox-active MIEC binder (symbolized by PT*-G(m)C(n)) was designed to be (1) electrically conductive along its conjugated thiophene backbone (PT = polythiophene), (2) redox-active from its succinimide moiety (* = redox-active) and (3) ionically conductive by adopting glyme (G) branches. It was superior to the practically used PVdF binder in terms of lithium ion diffusivity and electrical conductivity (1.4x and 15 000x, respectively). High capacity was guaranteed, particularly at high rates due to its MIEC nature of PT*-G(m)C(n), while an additional capacity was achieved from its redox activity.